Conventional snow throwers typically employ a large main blade for gathering and breaking up the ice and snow and one or more smaller impeller blades which collect the snow and discharge it from the machine through a discharge chute. If the chute clogs with ice and snow as it often does when wet snow, slush and/or freezing weather prevail, it becomes necessary to clean out and around the chute to permit proper snow throwing action to resume. However, this is an extremely hazardous maneuver because the impeller blades are whirling at an extremely high speed, typically less than an inch below the bottom of the chute opening and are invisible to the eye. It often becomes virtually impossible to determine the precise location of the whirling blades inside the housing rim during snow removal operations. Even the most careful operators have made misjudgments with unfortunate results. If the operator accidentally inserts a hand or fingers into this area of the chute, he risks being caught in a scissor-like manner between the blades of the powerful impeller and its housing. Even the slightest penetration of the operator's hands or fingers in the vicinity of the spinning impeller blades is liable to cause serious injury or maiming.
In an attempt to improve the safety of the discharge chute, one device, U.S. Pat. No. 3,921,315, employs a spring loaded "M" shaped element pivotally mounted in the chute and extending partially across the discharge opening thereof. However, this apparatus is largely ineffective in a number of snow throwers. The "M" shaped wire guard includes a number of relatively large gaps through which the operator's hands and fingers may be accidentally inserted. Moreover, the device provides virtually no protection across the critical bottom of the discharge opening. While brushing out ice and snow from the bottom of the chute the unsuspecting operator can easily slip a hand or finger beneath the wire "M" and dangerously close to the whirling impeller blades. Additionally, in many machines the spring is entirely omitted which permits the "M" element to flop uselessly out of the chute. As a result, the safety device provides absolutely no impedance to the introduction of the operator's hands or fingers. A further difficulty is the relatively smooth flowing lines of the wire "M" element which do not effectively warn the operator against, or inhibit him from, putting his hands or fingers too far into the discharge chute.